无机氮对土壤氮矿化与固定的影响——兼论土壤氮的“激发效应”

用室内培养和¹⁵N技术研究了土壤氮的矿化和固定,结果表明:无机氮添加不能引起土壤有机氮的加速分解;无机氮添加可显著增强添加氮的生物固定,但以减弱对土壤氮的固定为交换,因此培养期的总固定氮量并无显著增长。培养期间土壤净矿化氮因添加无机氮而有所增长,这一现象(时常被称为氮激发效应)看来主要是由于添加氮在土壤氮固定过程中替代了部分土壤氮之故。

THE EFFECT OF MINERAL NITROGEN ON THE MINIERALIZATION AND IMMOBILIZATION OF SOIL NITROGEN

Mineralization and immobilization of soil nitrogen were studied by incubation methods with labelled nitrogen. Results showed that deoamposition of organic nitrogen in soil was not accelerated by the mineral nitrogen added;however, the mineral nitrogen added in soil accelerated the biological immobilization of the nitrogen added, and, at the wane time, lowered the immobilization of soil nitrogen. Therefore, there was no dietinct fluctuation of the total immobilization nitrogen in soil in the whole period of in-cwbation. It seems that the increase of the net mineralized nitrogen in soil induced by mineral nitrogen added, which is generally Known as the priming effect, is mainly because part of soil nitrogen to be immobilized is replaced by mineral nitrogen added in soil.